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M. A. Bearse, Jr., K. Bronson-Castain, S. Jonasdottir, B. King-Hooper, J. Neuville, S. Barez, M. E. Schneck, A. Adams; Evidence for Retinal Neuropathy in Adolescents With Diabetes. Invest. Ophthalmol. Vis. Sci. 2009;50(13):4762.
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© ARVO (1962-2015); The Authors (2016-present)
The multifocal electroretinogram (mfERG) P1 implicit time (IT) delays observed in adult diabetes do not decrease normally with fast light adaptation, suggesting that they represent a form of retinal neuropathy (Bearse et al., ARVO 2008). This study examines whether similar abnormalities exist in adolescents with diabetes.
MfERGs were recorded from one eye of adolescent subjects without retinopathy aged 12.8 to 21.5 years. We studied 3 age-matched groups: 30 individuals with type 1 diabetes; 11 with type 2 diabetes; and 26 controls. Nine retinal regions were examined: the central 7.5 deg; 4 areas between 3.25-10.5 deg eccentricity; and 4 areas between 10.5-22.5 deg. Within each region, the mfERG kernel series was used to synthesize isolated flash responses evoked under 4 adaptation conditions: (1) no flashes in the 40 ms preceding the stimulus; (2) a flash 40 ms before the stimulus; (3) a flash 26.7 ms before; and (4) a flash 13.3 ms before. Responses evoked by the preceding flashes were removed. IT of each isolated adapted response was then measured. IT changes relative to condition 1 (no preceding flash) were also calculated. Measurements were converted to Z-scores based on the control data and Z-scores >= 2 were considered abnormal (P < 0.023). For each adaptation condition, an eye was categorized as abnormal if 2 or more of the 9 Z-scores were abnormal (P < 0.02).
As in normal adults, the effect of fast light adaptation (proximity of a preceding flash) on the controls’ isolated responses was a decrease in IT. The results of the 3 subject groups largely overlapped, with no significant differences among their means. However, the frequencies of eye abnormalities differed. In the type 1 group, 20%, 17%, 13% and 7% of the eyes had abnormally delayed IT for conditions 1 through 4, respectively. Based on IT change, 10%, 17% and 7% of their eyes were abnormal for conditions 2 through 4, respectively. In the type 2 group, 9%, 9%, 0% and 36% of the eyes were abnormal based on IT for conditions 1 through 4, respectively. Based on IT change, 9%, 18% and 36% of their eyes were abnormal for conditions 2 through 4, respectively. Controls had frequencies of abnormality < 3%.
Whereas mfERG IT is delayed in many eyes of adolescents with type 1 diabetes, IT abnormalities decrease with higher light adaptation. In contrast, adaptation does not decrease IT normally in many eyes of adolescents with type 2 diabetes, indicating greater neuropathic changes. The results suggest that subclinical neuropathy occurs in the retinas of many adolescents with diabetes.
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